The present invention relates to eyeglasses that have attachment lens, and more particularly, to eyeglasses that utilize magnets to hold the attachment lens in place while permitting the user to easily remove the attachment lens when desired.
It is often desirable for someone who wears eyeglasses to be able to selectively attach auxiliary lens to such eyeglasses, when desired. For example, someone who wears eyeglasses that have prescription lens may want to add auxiliary lens in the form of sunglasses. Since the user may want to change the auxiliary lens frequently, depending upon where the user is, it is imperative that the auxiliary lens be easily mounted on the eyeglasses and easily removed therefrom, as necessary. It is also highly desirable that the auxiliary lens be securely held in place on the eyeglasses when mounted thereon so that the auxiliary lens will not accidentally fall off while in use. This requirement becomes even more important when the eyeglasses are being worn by a user involved in sports or other activities that put a strain on the mounting arrangement of the auxiliary lens.
There are a wide variety of mechanical attachment mechanisms which, in most cases, hold the auxiliary lens securely in place, but these mechanisms are sometimes difficult and time consuming to operate, and they are subject to malfunction if some part of the mechanism becomes bent or otherwise damaged during use.
It is also known to provide magnetic connections between the eyeglasses and the auxiliary lens, and while these connections are usually easier to use than mechanical mounting arrangements, they may not provide a connection that is as secure as may be desired. For example, U.S. Pat. No. 5,416,537 discloses an eyeglass frame that has magnets embedded in the front face thereof, and the frame of the attachment lens is provided with protruding magnets that engage the embedded magnets to hold the attachment lens in place. In this arrangement, when the eyeglasses are being worn, the abutting surfaces of the two sets of magnets lie in a vertical plane, and provide the only means of support for the attachment lens. Therefore, the entire weight of the attachment lens must be borne solely by the abutting vertical faces of the magnets, and any activity of the wearer which results in up-and-down movement of the head of the user creates an additional load on the magnetic connection. If the magnets are made large enough to have sufficient magnetic force to hold the attachment lens securely in place, then it may be difficult for the user to overcome this large magnetic force when the user desires to detach the attachment lens.
In an effort to overcome the disadvantages of the aforesaid magnetic mounting, it has been proposed in U.S. Pat. No. 5,568,207 to arranged one of the sets of magnets on the eyeglass frame so that the magnetically engaging surface thereof lies in a horizontal plane in normal use, and the magnets on the attachment lens rest on the eyeglass magnets during engagement therewith. While this arrangement provides better support for the attachment lens by avoiding the vertically positioned surfaces of the aforesaid U.S. Pat. No. 5,416,537, the attachment lens are still held in place solely by the magnetically engaging surfaces, and are, therefore, still prone to being accidentally dislodged from the eyeglass frame, particularly by forces acting on the attachment lens in the horizontal plane of the magnetic engagement.
Accordingly, there is a need for a combination eyeglass frame and attachment lens which will have a secure magnetic and mechanical attachment between the two elements, while still permitting the attachment lens to be easily removed, when desired.